 (ns c2.geo.core
   (:use [clojure.core.match :only [match]]
         [clojure.string :only [join]]
-        [c2.maths :only [abs]])
+        [c2.maths :only [abs add sub div mul]])
   (:require c2.geom.polygon))
 
 (defn geo->svg

              (polygon-area xs)

              [{:type "MultiPolygon" :coordinates xs}]
              (apply + (map polygon-area xs))

              :else 0)))

  (defn polygon-area [poly-coordinates]
    (let [area (fn [coordinates]
                 (abs (c2.geom.polygon/area (map projection coordinates))))]

      ;;area of exterior boundary - interior holes
      (apply - (area (first poly-coordinates))
             (map area (rest poly-coordinates)))))

  (abs (match [geo]
